Integrated Validation of Coarse Remotely Sensed Evapotranspiration Products over Heterogeneous Land Surfaces

Validation of remotely sensed evapotranspiration (RS_ET) products is important because their accuracy critical for various scientific applications. In this study, an integrated validation framework was proposed evaluating RS_ET with coarse spatial resolution extending from homogenous to heterogeneous land surfaces. This applied at the pixel and river basin scales, using direct indirect methods multisource datasets, which solved mismatch between ground measurements products. The accuracy, rationality spatiotemporal variations, error sources uncertainties during process were focuses in framework. application exemplified by validating five widely used (i.e., GLEAM, DTD, MOD16, ETMonitor, GLASS) Heihe River Basin 2012 2016. Combined results (as priority method) auxiliary method), DTD showed highest (1-MAPE) vegetation growing season (75%), followed ETMonitor (71%), GLASS (68%), GLEAM (54%), MOD16 (44%). Each product reasonably reflected variations dataset. exhibited consistency truth ET scale (ETMap) (R = 0.69), (0.65), (0.63), (0.62), (0.57). Error these mainly due limitations algorithms input data, while amounted 15–28%. work effectively validate improve over